Uncontrolled pain is a major impediment to post-operative functional recovery. Despite major advances in the understanding and treatment of pain, under treatment of pain, particularly post-operative pain remains a persistent problem in the United States. Although data exist regarding the adverse outcome of untreated pain in younger adults as well as the beneficial effects of treating it, relatively little is known about the impact of post-operative pain on older adults - the most rapidly growing segment of the population. Older adults who undergo lower extremity orthopedic surgery (e.g., hip arthroplasty, knee arthroplasty, open reduction and internal fixation (ORIF)) experience intense post-operative pain and are at high risk for sub-optimal analgesic therapy. Higher pain levels following elective hip/knee arthroplasty and ORIF have been associated with increased lengths of stay in both acute care and rehabilitation hospitals, increased complications, delays in ambulation, aberrant gait patterns, impaired functional recovery at 6 months, and increased suffering. Given the paucity of data with respect to the effective treatment of pain in the geriatric patient, the rapid growth of the elderly population, and the increasing number of geriatric patients undergoing surgery - particularly orthopedic procedures- we propose to examine the effect of a multi-component and inter-disciplinary intervention designed to improve the detection and management of pain on functional and clinical outcomes in older adults admitted to an acute rehabilitation hospital following lower extremity orthopedic surgery. The intervention includes rigorous assessment of pain both at rest and with physical therapy, scheduled titration of analgesic medications to ensure patients are comfortable at rest and that pain does not interfere with transfers and ambulation, and pre-emptive analgesia prior to physical therapy to maximize the duration and intensity of rehabilitation. The analgesic protocol will be placed on one of 3 acute rehabilitation units at Mount Sinai Hospital. Patients from the intervention unit and 2 control units will be enrolled by means of a prospective matching strategy. The project will examine the impact of this generalizable intervention on pain levels, lower extremity performance, functional status, health related quality of life, and utilization.